BEIRUT (AP) — Government forces widened a bombing campaign in rebel-held areas of northern Syria on Monday, striking one of the main border towns near Turkey and killing 15 people, said activists.

The attack on Azaz was the latest attack using powerful but inaccurate “barrel bombs” on the northern city of Aleppo and its surrounding towns and villages, said an activist who goes by the name of Abu al-Hassan Marea. He said residents in the town told him that 15 people were killed in the strike. Another activist group, the Local Coordination Committees, gave the same death toll.

The Azaz attack suggests the government is expanding its range of targets a week after it began an unusually heavy air offensive against Aleppo on Dec. 15., dropping barrel bombs on rebel-held areas from helicopters. Aleppo, Syria’s largest city, is divided into government-and-rebel-ruled areas.

Barrel bombs are crude devices filled with explosives and fuel that are wildly inaccurate — often landing near schools and market places, causing massive damage on impact. In the first four days of the current air campaign alone, the aid group Doctors Without borders said the bombs killed at least 189 people and wounded 879.

The government has not commented on the use of the crude weapons, nor on the intensified strikes over Aleppo. But the timing suggests that Syrian President Bashar Assad could be trying to strengthen his position a month ahead of planned peace talks in Switzerland.

Government forces have struck towns outside of Aleppo in the past few days, but Azaz appears the furthest place from the city targeted so far by the barrel bombs.

Barrel bombs also struck the Aleppo neighborhoods of Qadi Askar and Marjeh on Monday, killing three people, said activist Marea and another activist who identifies as Abu Raed.

Also Monday, Syrian activists raised the death toll to 65 from a barrel bombing around a marketplace in the rebel-held Masaken Hanano area of Aleppo. It was one of the deadliest attacks since the Syrian military began its assault.

The British-based Syrian Observatory of Human Rights said mostly civilians were killed when helicopters dumped the explosives-laden barrels around the Masaken Hanano market on Sunday, hitting a series of cars, the road and flattening a two-story building.

Earlier, the Observatory said that 47 people were killed. The Observatory, which gathers information from a network of activists on the ground, said the death toll was raised after it was able to identify more victims.

Activist Hassoun Abu Faisal, of the Aleppo Media Center, said Monday that 83 people were killed. Such conflicting figures are common in the aftermath of large bombings.

Abu Faisal said part of the confusion was that many of the killed were badly burnt, or their bodies were torn apart by the blast, leaving medics to piece together macabre puzzles to count casualties. He said the intensity of the past weeks’ bombings also meant that ramshackle medical clinics were overwhelmed, and it was difficult to track where bodies — or body parts — were sent.

Medical groups have warned over the past week that local clinics have been overwhelmed by injuries and deaths caused by the barrel bombs. Abu Faisal said there was another looming crisis: the dozens of Syrians who were badly wounded in the attacks, needing prosthetic limbs or other expensive treatment.

“We are looking for aid groups to take care of the wounded. There’s nothing here for disabled people and most of the people who were injured are bread winners for their families,” he said.